TECHNOLOGIES FOR MODIFYING A FIRST CRYPTOGRAPHIC CIPHER WITH OPERATIONS OF A SECOND CRYPTOGRAPHIC CIPHER

• US 20150341168A1
• Filed: 05/21/2014
• Published: 11/26/2015
• Est. Priority Date: 05/21/2014
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: GUERON, SHAY
• Granted Patent: US 9,800,406 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 2209/24 Key scheduling, i.e. generating round keys or sub-keys for block encryption
• CPC Class Codes: H04L 9/06 the encryption apparatus using shift registers or memories for block-wise or stream coding, e.g. DES systems or RC4; Hash functions; Pseudorandom sequence generators
• CPC Class Codes: H04L 9/0838 Key agreement, i.e. key establishment technique in which a shared key is derived by parties as a function of information contributed by, or associated with, each of these network architectures or network communication protocols for key exchange in a packet data network H04L63/061
• CPC Class Codes: H04L 9/14 using a plurality of keys or algorithms

Abstract

Generally, the present disclosure provides technology modifying a first cryptographic cipher with one or more operations of a second cryptographic cipher. In some embodiments the technology leverages a mathematical relationship between representations of data used in the first and second ciphers to enable the substitution of one or more operations of the first cipher with one or more operations of the second cipher. The resulting modified cipher may in some instances exhibit improved performance and or security, relative to the unmodified first cipher. Methods, computer readable media, and apparatus including or utilizing the technologies are also described.

Claims

1. A method of executing a modified cryptographic cipher, comprising, with a processor:

executing a portion of operations of a first cryptographic cipher to produce a first representation of GF(2)⁸, REP1, wherein REP1 contains first data and is suitable for use in at least one operation of said first cryptographic cipher;

transforming REP1 to a second representation of GF(2)⁸, REP2, wherein REP2 contains said first data and is suitable for use in at least one operation of a second cryptographic cipher;

performing at least one isolated operation of said second cryptographic cipher using at least a portion of said first data in REP2 to produce a third representation of GF(2)⁸, REP3, wherein REP3 contains second data that is the output of said at least one isolated operation on said first data; and

transforming REP3 to a fourth representation of GF(2)⁸, REP4, wherein REP4 contains said second data and is suitable for use in at least one additional operation of the first cryptographic cipher.

2. The method of claim 1, wherein the method further comprises executing, after REP3 is transformed to REP4, at least one additional operation of said first cipher on at least a portion of said second data in REP4, wherein the at least one additional operation comprises performing a linear transformation of at least a portion of said data in REP4.

3. The method of claim 1, wherein said first cryptographic cipher is SMS4 and said second cryptographic cipher is the Advanced Encryption Standard.

4. The method of claim 3, further comprising:

prior to executing said at least one operation to produce REP1, transposing said first data to produce transposed data; and

performing said at least one operation on at least a portion of said transposed data to produce REP1.

5. The method of claim 3, wherein transforming REP1 to REP2 is performed at least in part with a first affine transformation based at least in part on a mapping matrix.

6. The method of claim 5, wherein transforming REP3 to REP4 is performed at least in part with a second affine transformation based at least in part on an inverse of said mapping matrix.

7. The method of claim 3, wherein performing at least one cryptographic operation of said second cryptographic cipher comprises, with said processor, executing a combination of Advanced Encryption Standard instructions on at least a portion of the first data in REP2, the combination of Advanced Encryption Standard instructions comprising at least an Advanced Encryption Standard Encrypt Last (AESENCLAST) comprising a Shift Rows transformation and a Substitute Bytes transformation.

8. The method of claim 7, further comprising:

executing an Inverse Shift Rows operation after execution of said AESENCLAST instruction and prior to transforming REP3 to REP4.

9. At least one computer readable medium comprising computer readable instructions which when executed by a processor cause the processor to perform the following operations comprising:

execute a portion of operations of a first cryptographic cipher to produce a first representation of GF(2)⁸, REP1, wherein REP1 contains first data and is suitable for use in at least one operation of said first cryptographic cipher;

transform REP1 to a second representation of GF(2)⁸, REP2, REP2 containing said first data and being suitable for use in at least one operation of a second cryptographic cipher;

perform at least one cryptographic operation of said second cryptographic cipher using at least a portion of said first data in REP2 to produce a third representation of GF(2)⁸, REP3, REP3 containing second data that is the output of said at least one cryptographic operation of said second cryptographic cipher; and

transform REP3 to a fourth representation of GF(2)⁸, REP4, wherein REP4 contains said second data and is suitable for use in at least one additional operation of the first cryptographic cipher.

10. The at least one computer readable medium of claim 9, wherein said instructions when executed cause said processor to perform the following additional operations comprising:

after REP3 is transformed to REP4, execute at least one additional operation of said first cipher on at least a portion of said second data in REP4, wherein said at least one additional operation of said first cryptographic cipher comprises performing a linear transformation of at least a portion of said second data in REP4.

11. The at least one computer readable medium of claim 9, wherein said first cryptographic cipher is SMS4 and second cryptographic cipher is the Advanced Encryption Standard.

12. The at least one computer readable medium of claim 11, wherein said instructions when executed cause said processor to perform the following additional operations comprising:

prior to executing said at least one operation to produce REP1, transpose said first data to produce transposed data; and

perform said at least one operation to produce REP1 on at least a portion of said transposed data.

13. The at least one computer readable medium of claim 11, wherein said instructions when executed further cause said processor to transform REP1 to REP2 at least in part with a first affine transformation based at least in part on a mapping matrix.

14. The at least one computer readable medium of claim 13, wherein said instructions when executed further cause said processor to transform REP3 to REP4 at least in part with a second affine transformation based at least in part on an inverse of said mapping matrix.

15. The at least one computer readable medium of claim 14, wherein said instructions when executed cause said processor to perform said at least one cryptographic operation of said second cryptographic cipher at least in part by executing a combination of Advanced Encryption Standard instructions on at least a portion of the first data in REP2, the combination of Advanced Encryption Standard instructions comprising at least an Advanced Encryption Standard Encrypt Last (AESENCLAST) comprising a Shift Rows transformation and a Substitute Bytes transformation.

16. The at least one computer readable medium of claim 15, wherein said instructions when executed cause said processor to execute an Inverse Shift Rows operation after execution of said AESENCLAST instruction and prior to transforming REP3 to REP4.

17. An apparatus, comprising:

a processor; and

a memory having a cipher operations module stored thereon, the cipher operations module comprising computer readable COM instructions for a modified cryptographic cipher on the processor, wherein said COM instructions when executed by said processor cause said processor to;

execute a portion of operations of a first cryptographic cipher to produce a first representation of GF(2)⁸, REP1, wherein REP1 contains first data and is suitable for use in at least one operation of said first cryptographic cipher;

transform REP1 to a second representation of GF(2)⁸, REP2, REP2 containing said first data and being suitable for use in at least one operation of a second cryptographic cipher;

perform at least one cryptographic operation of said second cryptographic cipher using at least a portion of said first data in REP2 to produce a third representation of GF(2)⁸, REP3, wherein REP3 contains second data that is the output of said at least one cryptographic operation of said second cryptographic cipher; and

transform REP3 to a fourth representation of GF(2)⁸, REP4, wherein REP4 contains said second data and is suitable for use in at least one additional operation of the first cryptographic cipher.

18. The apparatus of claim 17, wherein said COM instructions when executed cause said processor to perform the following additional operations comprising:

after REP 3 is transformed to REP4, execute at least one additional operation of said first cipher on at least a portion of said second data in REP4, wherein the at least one additional operation comprises performing a linear transformation of at least a portion of said data in REP4.

19. The apparatus of claim 17, wherein said first cryptographic cipher is SMS4 and said second cryptographic cipher is AES.

20. The apparatus of claim 19, wherein said COM instructions when executed cause said processor to perform the following additional operations comprising:

prior to executing said at least one operation to produce REP1, transpose said first data to produce transposed data; and

perform said at least one operation to produce REP1 on at least a portion of said transposed data.

21. The apparatus of claim 19, wherein said COM instructions when executed further cause said processor to transform REP1 to REP2 at least in part with a first affine transformation based at least in part on a mapping matrix.

22. The apparatus of claim 21, wherein said COM instructions when executed further cause said processor to transform REP3 to REP4 at least in part with a second affine transformation based at least in part on an inverse of said mapping matrix.

23. The apparatus of claim 19, wherein said COM instructions when executed cause said processor to perform said at least one cryptographic operation of said second cryptographic cipher at least in part by executing a combination of Advanced Encryption Standard instructions on at least a portion of the first data in REP2, the combination of Advanced Encryption Standard instructions comprising at least an Advanced Encryption Standard Encrypt Last (AESENCLAST) comprising a Shift Rows transformation and a Substitute Bytes transformation.

24. The apparatus of claim 23, wherein said COM instructions when executed cause said processor to execute an Inverse Shift Rows operation after execution of said AESENCLAST instruction and prior to transforming REP3 to REP4.